Unless deploying a new network (i.e., a green-field application deployment), introducing SDN products and protocols in the network involves migration from conventional network systems and methods, e.g. control planes, to include hybrid SDN capabilities. Thus, the network must be designed to support SDN protocols on both physical and virtual switching environments, with a management framework to support both SDN and conventional protocols. A hybrid network provides the advantage of offering enterprise Information Technology (IT) a gradual migration from its current network architecture. This means the ability to leverage existing networks without having to rip and replace the network. Hybrid SDN and traditional networking appeals to IT organizations looking to gain the benefits of SDN, which include improved provisioning, network flexibility, Quality of Service (QoS) and programmability during the SDN migration.
Also, in some cases, moving certain control plane functionality from Network Elements (NEs) to an SDN Controller is not feasible, and it is very difficult to meet the performance of the NEs control plane especially in a multi-layer network. So, it is necessary to leverage the existing Layer 1 and Layer 0 Control Plane of the NEs without having to sacrifice the performance. Exemplary control planes may include Automatically Switched Optical Network (ASON) as defined in ITU-T G.8080/Y.1304, Architecture for the automatically switched optical network (ASON) (02/2005), the contents of which are herein incorporated by reference; Generalized Multi-Protocol Label Switching (GMPLS) Architecture as defined in IETF Request for Comments (RFC): 3945 (10/2004) and the like, the contents of which are herein incorporated by reference; Optical Signaling and Routing Protocol (OSRP) from Ciena Corporation which is an optical signaling and routing protocol similar to PNNI (Private Network-to-Network Interface) and MPLS; or any other type control plane for controlling network elements at multiple layers, and establishing connections therebetween.
Also, there can be a hierarchical dependency for certain applications, in SDN, control planes, or the like. For example, an Element Management System (EMS) can synchronize the data from the Network Elements in the network. A Network Management System (NMS) has to wait for EMS synchronization to complete, and then it synchronizes the data from EMS. Higher-level applications get the network data from the NMS or an SDN Controller. So, for higher-level applications, the EMS and NMS have to be synchronized first. This approach leads into performance and data integrity issues.